Designed to reduce the amount of sludge produced and related water losses, Actiflo® HCS (for High Concentration Sludge) is an Actiflo system equipped with an outside recycling loop.


ACTIFLO® HCS’ principal feature is that it comes with a specific hydrocylone* and an external recirculation loop. 

After settling, the sludge/microsand mixture is pumped to the hydrocyclone where the microsand is thoroughly washed before being injected back into the flocculation tank. The flow of sludge is directed in part towards the recirculation loop with the other part being discharged. Thanks to a fine regulation system, Actiflo HCS reduces the amount of sludge produced by 2 to 3 times, while still maintaining a high clarification level.




  • A 50 – 80% reduction in sludge volume
  • Water losses reduced to under 0.5%
  • A reduction (in size and number) of the facilities used to treat dirty water/sludge from the Actiflo
  • Easy to implement in refurbishing projects


  Flow m3/h Turbidity HCS
% open
Cyclone  Feed

Sludge DIscharge

    In Out     m3/h mg/l
ACTIFLO 43 7 0.8 0 2.5 2.4 980
ACTIFLO HCS 44 6 0.8 42 2.5 0.26 9 200



Municipal drinking water

  • Chomedey, Laval (Greater Montreal), Canada, 2013, 273,000 m3/day Treating river water/high turbidity peaks, decanting rate: 68 m/h
  • Pont Viau, Laval (Greater Montreal), Canada, 2013, 135,000 m3/day Treating river water/high turbidity peaks, decanting rate: 40 m/h
  • Gitanmaax Band Village, Hazelton, Indian Reserve, Canada, 2012, 1,400 m3/day Treating river water, decanting rate: 55 m/h
  • Okotoks Ground, Canada, 2011, 22,000 m3/day, Treating turbidity peaks, decanting rate: 54 m/h


Industrial applications

  • Japan Nippon Steel & Sumitomo Metal, Kimitsu, Japan, 2014, 14,000 m3/day Treating effluents (metals, coke and coal dust),decanting rate: 120 m/h
  • Nippon Steel & Sumitomo Metal, Kimitsu, Japan, 2014, 40,000 m3/day, Treating effluents (metals, landfill leachate, urban rain water), decanting rate: 100 m/h
  • CEZ Pocerady, Czech Republic, 2011, 24,000 m3/day Treating river water to produce process water for boiler cooling (in the energy sector) Actiflo HCS, 40 m/h



ACTIFLO® HCS is applicable to several industrial and municipal situations.

Municipal applications

  • Treatment of river water and turbidity peaks

Industrial applications

  • Effluents treatment
  • Process water production

Resources & Product range